Gas fired radiant emitters comprising a perforated ceramic burner plate as combustion surface (burner deck) are well known. Such emitters are e.g. used in continuous ovens, e.g. for treating (e.g. drying or curing) continuous webs or sheets, e.g. coatings on paper. The gas fired radiant emitters can be provided with radiant screens in order to increase efficiency. WO2010/018037A1 and WO2010/03904 show examples of such radiant emitters.
The emitters need to be ignited at start-up of the installation. A known way to ignite the emitters is by using a pilot burner appropriately positioned near the burner deck of one or more emitters. A gas premix flows through and exits a tube of the pilot burner. A spark is generated between two electrodes of the pilot burner, thereby igniting the gas premix supplied through the tube of the pilot burner. The flame of the pilot burner subsequently ignites the gas flowing through the perforated ceramic burner deck.
During use of the installation, flame detection is required on the combustion surface of the emitters. If no combustion is detected at the emitters, the supply of combustible gas to the emitters has to be stopped as soon as possible in order to prevent safety incidents. A flame detection pilot burner is frequently used to this end. The flame detection pilot burner is positioned near the combustion surface of the emitters. It comprises a tube through which a gas premix flows. At the exit of the tube, the gas premix is ignited by presence of combustion on the burner deck of the gas fired radiant emitter. The flame detection pilot burner comprises two electrodes, through which ionization current flows when the gas premix flowing through the tube is ignited. Detection of the ionization current indicates that combustion takes place on the burner deck of the emitter. When no combustion takes place on the burner deck, there will no longer be combustion of the premix gas flowing through the tube. When ionization current is no longer measured, absence of combustion on the burner deck is detected and gas supply to the burner deck can be stopped via specific control means.
DE4329194A1 describes a premixing burner with a flame outlet surface of perforated ceramic being ignited by a likewise premixing pilot burner integrated into the radiant main burner. The pilot burner itself is ignited, in a known manner, piezoelectrically, with battery ignition or the like. The radiant main burner and pilot burner utilise the same perforated ceramic plate as flame outlet surface and form a constructional and functional unit. In a burner described as an exemplary embodiment, the distribution space of the pilot burner is integrated into the distribution space of the radiant main burner. The mixing tube of the pilot burner is screwed into the distribution space of the pilot burner through the wall of the distribution space of the radiant main burner. The sealing between the distribution space of the pilot burner and flame outlet surface is provided by means of silicone adhesive, thereby at the same time guaranteeing a gastight separation of radiant main burner and pilot burner.